In the aerosol industry, overcaps of the type which engage and operate valve buttons have been widely used for a period of several years. Such overcaps improve the appearance of the aerosol container, allow incorporation of tamper-proof devices and/or safety devices, guide the consumer in his use of the can, and facilitate stacking of the aerosol containers. The overcap usually has a shape indicating the direction in which the aerosol contents are to be sprayed and physical characteristics such as a window exposing the spray orifice to accommodate spraying. Such overcaps, therefore, must be rotationally aligned with the aerosol spray button.
In some cases the overcap and button are integrally molded to eliminate any need for concern regarding alignment. In other cases, the overcap and button are locked together prior to being mounted on the aerosol container. In still other cases an overcap is placed over the button and secured to the container after the button has been attached to the aerosol valve stem. The present invention applies to overcap and button combinations of the latter type. In such devices the overcap has an actuator tab which engages the button and which is used to depress or tilt the button (and thus the valve stem) for spraying.
A number of devices and methods for placing an overcap over an aerosol spray button and aligning the overcap with the button have been described and used in the prior art, including those disclosed in U.S. Pat. Nos. 3,674,184, 3,589,570, 3,738,541, 3,407,975, and 4,132,333. Devices and methods of the prior art, however, have had significant problems which the present invention is intended to solve, by providing a functionally superior, self-aligning, aerosol dispensing device of the overcap and button type.
The overcap and button typically have cooperating means which maintain the proper relative rotational alignment once such proper alignment is attained. The cooperating means usually consist of a key and a keyway formed in the adjacent surfaces of the button and overcap although other means can be used. Certain devices of the prior art include inclined ledges or ramps formed in the element having the keyway, such ledges or ramps being engageable by the key so as to allow or produce relative rotation of the button and overcap to bring them into the proper alignment.
Some overcap and button combinations of the prior art have drawbacks in that they require special assembly equipment to properly place the overcap on the button and/or to rotate the overcap with respect to the button to achieve the necessary alignment. Even though some of the devices of the prior art are intended to come into alignment by a relative rotating motion under the force of gravity, such action often fails because of improper placement of the overcap on the button or other interference preventing sufficient relative rotation to achieve alignment.
A specific problem is the periodic failure of gravitational alignment in prior art devices of the type having a button with slanted peripheral top surface which provides a slanted camming surface for engagement by a key of the corresponding overcap. Such failures occur, unless special assembly equipment is used, due to the occasional failure of the key to engage the slanted camming surface. Rather than engaging the camming surface, the key sometimes engages the side wall of the button thus preventing the necessary relative rotational movement.
Another problem is failure of alignment due to dimensional variations, burrs, and the like. In the key-keyway systems of the prior art, variations can cause a failure of proper cooperating engagement which prevents the intended aligning motion.
In summary, there is a need in the aerosol packaging industry for an overcap-button device which is reliably self-aligning, and which can come into alignment without the need for special assembly equipment.